ssa: make block with label name for debug readable

cl/compile.go

@@ -318,7 +318,7 @@ func (p *context) compileBlock(b llssa.Builder, block *ssa.BasicBlock, n int, do
 		modPtr := pkg.PyNewModVar(modName, true).Expr
 		mod := b.Load(modPtr)
 		cond := b.BinOp(token.NEQ, mod, prog.Nil(mod.Type))
-		newBlk := fn.MakeBlock()
+		newBlk := fn.MakeBlock("")
 		b.If(cond, jumpTo, newBlk)
 		b.SetBlockEx(newBlk, llssa.AtEnd, false)
 		b.Store(modPtr, b.PyImportMod(modPath))

ssa/decl.go

@@ -293,13 +293,15 @@ func (p Function) MakeBlocks(nblk int) []BasicBlock {
 		p.blks = make([]BasicBlock, 0, nblk)
 	}
 	for i := 0; i < nblk; i++ {
-		p.addBlock(n + i)
+		p.addBlock(n+i, "")
 	}
 	return p.blks[n:]
 }
 
-func (p Function) addBlock(idx int) BasicBlock {
-	label := "_llgo_" + strconv.Itoa(idx)
+func (p Function) addBlock(idx int, label string) BasicBlock {
+	if label == "" {
+		label = "_llgo_" + strconv.Itoa(idx)
+	}
 	blk := llvm.AddBasicBlock(p.impl, label)
 	ret := &aBasicBlock{blk, blk, p, idx}
 	p.blks = append(p.blks, ret)
@@ -307,8 +309,8 @@ func (p Function) addBlock(idx int) BasicBlock {
 }
 
 // MakeBlock creates a new basic block for the function.
-func (p Function) MakeBlock() BasicBlock {
-	return p.addBlock(len(p.blks))
+func (p Function) MakeBlock(label string) BasicBlock {
+	return p.addBlock(len(p.blks), label)
 }
 
 // Block returns the ith basic block of the function.

ssa/eh.go

@@ -162,7 +162,7 @@ func (b Builder) getDefer(kind DoAction) *aDefer {
 		czero := prog.IntVal(0, prog.CInt())
 		retval := b.Sigsetjmp(jb, czero)
 		if kind != DeferAlways {
-			rundBlk = self.MakeBlock()
+			rundBlk = self.MakeBlock("")
 		} else {
 			blks = self.MakeBlocks(2)
 			next, rundBlk = blks[0], blks[1]
@@ -228,7 +228,7 @@ func (b Builder) Defer(kind DoAction, fn Expr, args ...Expr) {
 // RunDefers emits instructions to run deferred instructions.
 func (b Builder) RunDefers() {
 	self := b.getDefer(DeferInCond)
-	blk := b.Func.MakeBlock()
+	blk := b.Func.MakeBlock("")
 	self.runsNext = append(self.runsNext, blk)
 
 	b.Store(self.rundPtr, blk.Addr())

ssa/stmt_builder.go

@@ -94,7 +94,7 @@ func (b Builder) setBlockMoveLast(blk BasicBlock) (next BasicBlock) {
 
 	impl := b.impl
 
-	next = b.Func.MakeBlock()
+	next = b.Func.MakeBlock("")
 	impl.SetInsertPointAtEnd(next.last)
 	impl.Insert(last)